More than two decades ago, epidemiologists began showing that increased exposure to airborne particulate matter (PM) leads to increased morbidity and mortality. By the end of 2011, teams of investigators across the United States had shown that exposure to PM increased incidence of numerous conditions including cardio-pulmonary disease, neurological damage, compromised immune function, low birth weight and possibly diabetes.
Increased exposure assessment has been recommended to link health effects to where and when people receive exposure to PM, with considerable attention to susceptible populations such as the elderly and people with chronic illnesses such as asthma. Extensive personal exposure assessment is needed to address environmental justice issues that increase the vulnerability of people who live near PM sources such as highways and/or in congested urban areas.
PM generally refers to a mixture of solid and liquid droplets suspended in air. PM includes various airborne pollutants such as dust, smoke, diesel exhaust, smog, ash and the like. PM can range in size from less than 2.5 μM to at least 10 μM in diameter, where fine particles (2.5 μM in diameter or less) being especially dangerous to a person's health due to the ability of the fine particles to pass thorough conventional air filters and to penetrate the body's natural filtering mechanisms, thereby entering the lungs and bloodstream. As such, having a mechanism to accurately measure PM concentrations can help identify sources of PM, as well as provide feedback in instances where reduction practices of PM are currently in use or are being tested.
While significant progress has been made in improving PM sensors, existing PM sensors used to measure PM concentration tend to be expensive and bulky, rendering them unable to provide detailed measurement information relevant to personal PM exposure at varied locations. Even with the more recent development of small scaled PM sensors, these still suffer from being too large to allow large-scale deployment as personal PM monitors.
Accordingly, there is a need for a device and method to improve the sensitivity of a current PM sensors that are user wearable, inexpensive and robust. The present invention addresses that need.